1. Field of the Invention
The invention relates to a sprung mass damping control system of a vehicle, which suppresses sprung mass vibration generated in the body of a vehicle. The invention also relates to a vehicle provided with that sprung mass damping control system.
2. Description of the Related Art
Technology referred to as sprung mass damping control that suppresses sprung mass vibration generated in a vehicle body using predetermined vibration damping means is well known. For example, Japanese Patent Application Publication No. 2004-168148 (JP-A-2004-168148) describes a technology that controls the driving force of a vehicle in order to suppress sprung mass vibration in the vehicle. In the technology described in JP-A-2004-168148, the driving force is controlled by increasing or decreasing the engine torque. To perform this control, these technologies increase or decrease the engine torque as necessary by adjusting the intake air amount, the fuel injection amount, and the ignition timing and the like of the engine.
Incidentally, Japanese Patent Application Publication No. 9-220919 (JP-A-9-220919) describes technology in which the phase of a control command signal of active suspension is adjusted.
The engine which is a drive source operates in various states, e.g., at various speeds, while running. Therefore, in any given operating state, the wheel speed of the driving wheels is affected by the output of the engine and thus fluctuates. As a result, the output responsiveness of a sprung mass damping control amount (i.e.; a control amount for suppressing sprung mass vibration) that is obtained using this wheel speed may decrease. Also, it is conceivable that sprung mass damping control may be executed using the output from the motor-generator which is also a drive source. However, the output responsiveness of the sprung mass damping control amount obtained using this wheel speed may end up decreasing depending on the waveform signal modulation method when controlling that motor-generator. Furthermore, in a vehicle according to related art, the responsiveness of the drive source may also change for a reason other than those described here, which may result in reduced output responsiveness of the sprung mass damping control amount. In this way, in a vehicle according to related art, the responsiveness of the drive source may decrease in a given situation, which may end up reducing the output responsiveness of the sprung mass damping control amount. As a result, the damping effect of sprung mass damping control may decrease. That is, there is room for improvement in sprung mass damping control of the related art.